The preparation of sterile liquid compounds, including emulsions and solutions, is well known. In certain cases it is necessary to sterilize the resulting liquid compound prior to using it for its intended purpose. Sterile filtration and heat-processing are well-known techniques for the terminal sterilization of such liquid compounds.
In certain situations it is preferable to provide a system that aseptically produces the liquid compound, thereby obviating the need for terminal sterilization of the compound. For example, it is possible that terminal sterilization will damage certain characteristics of the liquid compound. In the course of aseptic processing of a liquid compound it is usually necessary to add components of the compound into the aseptic processing system, thus requiring that each added component be sterile when it is introduced into the system. However, in many cases one or more of these components is provided in a non-sterile form. In order to ensure that each component is sterile when it enters the processing system, a sterilizing-grade filter or other known sterilization process can be used to sterilize the ingredient immediately prior to its introduction into the system.
It is difficult to ensure the accurate delivery of a pre-measured amount of a component when a sterilizing-grade filter is used due to the fact that the filter tends to retain a quantity of the component during filtration. In order to overcome this shortcoming of sterile filtration techniques, some prior art systems have employed a pre-sterilized hypodermic syringe to introduce sterile ingredients into a septum or injection site associated with the processing system. However, this technique can be cumbersome and is prone to failure due to the need to maintain the sterility of both the syringe and the septum or injection site, as well as the need to sterilize the component prior to its introduction into the hypodermic syringe.
The present invention contemplates an arrangement whereby a sterile ingredient that has been sterilized through the use of a sterile-grade filter can be efficiently and accurately added to a processing system, such as that used in the production of a sterile emulsion.